All the KOA's have cabins.
BUT
There are 3 types of cabins they rent.
1.One is completely furnished and is like a small house.
2.One has a bed but you have to bring your own linens.
3.The third one is called primitive. It has nothing in it but a wooded structure to lay on. No mattress, no bathroom!
And
Some of the KOA's CG's have camping 'Lodges'. Well those are just over the top!!!
If you want to still enjoy the CG experience but without your RV the KOA CG furnished cabin is REAL nice.
http://koa.com/lodges-cabins-cottages/